Infusion set of self-occlusion mechanism

ABSTRACT

A device, system and method for occluding fluid flow through an infusion set detached from a patient&#39;s body. The device includes a means for detecting loss of contact to a patient&#39;s body and activating an occlusion mechanism accordingly.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to subcutaneous delivery of medication viaa drug delivery system and, in particular is concerned with blocking theflow of medication when an infusion set becomes disconnected from thebody of the patient. The self-occluding infusion set may be usedtogether with a delivery system sensitive to flow blockage in order totrigger an alarm under circumstances in which the medication wouldotherwise be delivered outside the patient's body.

It is known that automated drug delivery systems provide a reliablemeans for administering medication at a prescribed dosage over anextended period. These systems typically include a medication pumpconnected to an infusion set attachable directly to the patient's body,and a cannula for delivering the medication subcutaneously. Under normalcircumstances the medication flows through the system into the patient'sbody in a controlled and consistent manner. However, such automationalone is not failsafe; fluid flow blockage (occlusion) occasionallyoccurs, preventing delivery of the medication to the patient. To addresssuch problems, most drug delivery systems include an alarm systemdesigned to alert the user when a blockage occurs so that he may takeappropriate measures. Occlusion of the flow path results in a suddenincrease in backpressure in the drug outlet flow path, thereby renderingthe malfunction relatively easy to detect.

A more problematic situation is caused if the infusion set becomesdisconnected from the patient's body. In this case, there is typicallyno detectable change in operating pressure along the flow path, suchthat the system may continue to deliver medication outside the bodywithout generating any indication of malfunction. This may leave thepatient oblivious to the fact that he is not receiving the requiredmedication, resulting in a potentially life threatening situation evenduring waking hours and particularly during sleeping hours.

There is therefore a need for an infusion set that facilitates thedetection of non-delivery of medication to the patient in situations theinfusion set has become disconnected from the body.

SUMMARY OF THE INVENTION

The present invention is a device, a system and a method for occludingfluid flow through an infusion set when the infusion set has becomedisconnected from a patent's body.

According to the teachings of the present invention there is provided,an infusion set for administering a fluid through the skin, the infusionset comprising: (a) a cannula having a lumen for fluid transfer throughthe skin; (b) a retention arrangement maintaining an inserted positionof said cannula through the skin; and (c) a self-occlusion mechanismassociated with said retention arrangement and with said cannula, saidself-occlusion mechanism being configured such that, while saidretention arrangement maintains an inserted position of said cannula,said self-occlusion mechanism is retained in a first non-occluding stateand, if said retention arrangement ceases to maintain the insertedposition of said cannula, said self-occlusion mechanism assumes a secondstate in which said self-occlusion mechanism at least partially occludesfluid flow through said cannula.

According to a further feature of the present invention, an inserterneedle initially inserted in the lumen of said cannula such that saidinserted needle prevents said self-occlusion mechanism from assumingsaid second state prior to withdrawal of said inserter needle.

According to a further feature of the present invention the retentionarrangement includes an adhesive material applied to the underside ofsaid infusion set.

According to a further feature of the present invention theself-occlusion mechanism includes a biasing element to resiliently biassaid mechanism to assume said second state.

According to a further feature of the present invention the biasingelement includes a leaf spring.

According to a further feature of the present invention the selfocclusion mechanism includes a constriction element to occlude saidcannula.

According to a further feature of the present invention the constrictionelement includes a rotatably mounted cam.

According to a further feature of the present invention the constrictionelement includes a slideably mounted constriction element.

According to a further feature of the present invention the constrictionelement is implemented as an integrally biased cannula.

According to a further feature of the present invention theself-occlusion mechanism is configured to fully occlude said cannula.

There is also provided according to the teachings of the presentinvention a system for detecting disconnection of an infusion set fromthe skin of a subject, the system comprising: (a) a drug delivery deviceconfigured to deliver a controlled flow of a liquid drug, the drugdelivery device including an arrangement for detecting occlusion of anoutlet flow path; (b) an infusion set connected to said outlet flowpath, said infusion set including a cannula for delivering the liquiddrug through the skin of the subject; and (c) a self-occlusion mechanismassociated with said infusion set, said self-occlusion mechanism beingconfigured such that, when said cannula is removed from the skin of thesubject, the self-occlusion mechanism at least partially occludes fluidflow through said infusion set.

There is also provided according to the teachings of the presentinvention a method for facilitating detection of malfunction duringdelivery of a drug via an infusion set through the skin of a patient,the method comprising the steps of: (a) providing a flow-path from adrug delivery device via an infusion set through the skin of thepatient;

(b) providing a flow-path from a drug delivery device via an infusionset through the skin of the patient; (c) responsive to at least partialfailure of said retention arrangement to retain the part of the infusionset secured against with the skin, generating at least partial occlusionof the flow path.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 is an isometric view of a cam variant of a constriction-basedembodiment of an infusion set.

FIG. 2 is an isometric view of the underside of the cam variant of aconstriction-based embodiment of an infusion set.

FIG. 3 is sectional view of the can variant of the constriction-basedembodiment.

FIGS. 4A and 4B are schematic drawings of the cam variant of theconstriction-based embodiment depicting a leaf-spring configuration inits loaded and unloaded states respectively.

FIGS. 5 through 7 are sectional views of a variant form of theconstriction-cam embodiment in its insertion state, non-occludedoperative state and detached occluded state, respectively.

FIG. 8 is an exploded isometric view of a slideable-block variant of theconstriction-based embodiment of a self-occluding infusion set.

FIGS. 9 and 10 are sectional views of the infusion set of FIG. 8assembled, shown in its occluded and non-occluded states, respectively.

FIGS. 11A and 11B depict the underside of a second slideable-blockvariant form of the constriction-based embodiment in its occluded andnon-occluded states.

FIG. 12 is an exploded view of a third slideable-block variant form of aconstriction-based embodiment of a self-occluding infusion set.

FIGS. 13A and 13B are underside views of the infusion set of FIG. 12assembled, shown in its occluded and non-occluded states, respectively.

FIGS. 14A and 14B are views of a third slideable-block variant form of aconstriction-based embodiment of a self-occluding infusion set showingan integral hinge arrangement in its occluded and non-occluded states,respectively.

FIGS. 15 through 17 are sectional views of a spring variant form of theconstriction-based self-occluding infusion set shown in its insertionstate, its non-occluded operating state and its detached occluded state,respectively.

FIG. 18 is an exploded isometric view of a first form of ablockage-based embodiment of the self-occluding infusion set.

FIG. 19 is a sectional view of the infusion set of FIG. 18 assembled, inits operative, un-occluded state.

FIG. 20 is a close-up sectional view of the infusion set of FIG. 19.

FIG. 21 is a sectional view of the infusion set of FIG. 18 in itsassembled, in its operative, un-occluded state.

FIG. 22 is a close-up sectional view of the infusion set of FIG. 21.

FIGS. 23-25 are sectional views of a second variant form of ablockage-based embodiment of an infusion set in its insertion state,operative non-occluded state, and occluded state, respectively.

FIGS. 26 and 27 are sectional views of a kink-based embodiment in itsnon-occluded operational state and detached occluded state,respectively.

FIG. 28 is an isometric view of an automated medicine delivery system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a mechanism, system, and corresponding methodfor a drug delivery system for automatically occluding fluid flowthrough an infusion set when the cannula becomes disengaged from apatient.

The principles and operation of the various implementations according tothe present invention may be better understood with reference to thedrawings and the accompanying description. The mechanism of the presentinvention will be illustrated herein with reference to a number ofnon-limiting examples. Three general embodiments, based on the manner ofocclusion, will be described in reference to the figures as follows:

-   -   A first implementation constricts a flow passageway, i.e.,        deforms a wall of the passageway by application of external        forces sufficient to substantially occlude flow, as will be        described with reference to FIGS. 1-7.    -   A second implementation introduces an obstruction so as to        substantially block a flow passageway, as will be described with        reference to FIGS. 8-25.    -   A third implementation kinks or otherwise deforms the shape of a        flow passageway, which may be the projecting portion of the        cannula, as will be described in reference to FIGS. 26-27.

Although the invention will be described with reference to particularocclusion mechanisms falling within one of the above groups, it shouldbe noted that the invention is not limited to these implementations, andmay be implemented using any mechanism effective to selectively occludesome part of the drug delivery flow path, as will be clear from thefollowing description.

Before addressing the details of the exemplary embodiments, it should beappreciated that, as mentioned above, all of the various embodimentsshare a common operational principle, corresponding to a device, systemand method of the present invention. Specifically, as noted above, it iscommon for drug delivery systems to include an arrangement for detectingblockage of the flow path and generating an alarm to the user, whereasinadvertent disconnection of the infusion set from the body is moredifficult to reliably detect. To address this problem, the presentinvention provides an infusion set modified by a self-occlusionmechanism configured to block flow through the infusion set in the eventthat the infusion set becomes disconnected from the body. This convertsthe hard-to-detect condition of disconnection into the easier-to-connectcondition of occlusion, thereby facilitating detection of themalfunction and timely warning to the user.

Although the invention is described herein in preferred implementationsin which the flow through the infusion system is typically completelyoccluded, it should be noted that implementations causing partialocclusion are also within the scope of the invention. Incompleteocclusion sufficient to cause increased back-pressure in the drugdelivery flow path is also detected by many drug delivery systems as anerror condition requiring intervention, and may therefore be used in thecontext of the present invention.

It should be noted that the terms “disconnected” or “detached” refer toa loss of contact between the infusion set and the body sufficient toimpact the position of the cannula. Therefore, for the purposes of thisdefinition there is no distinction made between a situation in which theinfusion set together with the cannula loose complete contact with thebody and a situation in which the infusion set looses contact while thecannula remains inserted because the cannula will inevitably bewithdrawn from patient's body almost immediately after the infusionlooses contact. Furthermore, a condition in which the infusion setremains partially in contact with the body but no longer providesreliable positioning of the cannula is also referred to as“disconnected” or “detached”.

Furthermore, regarding terms of usage, the term “self-occluding” refersto any functionality provided by any combination of elements includedwithin or externally associated with the infusion set eliminating theneed for manual intervention for occluding fluid-flow through theinfusion set.

In certain cases, an electrically or otherwise remotely operable flowoccluding device may be actuated in response to sensing of disconnectionof the infusion set from the body.

Following is a general description of the structure common to all of theembodiments presented here within.

The self-occluding infusion set is a device for administering a fluidthrough the skin; including a cannula having a lumen for fluid transferthrough the skin, a retention arrangement providing the infusion setattachment to the body so as to maintain an inserted position of thecannula through the skin; and a self-occlusion mechanism associated withthe retention arrangement and with the cannula so that theself-occlusion mechanism is configured such that, while the retentionarrangement provides attachment of the infusion set to the body, theself-occlusion mechanism is retained in a first non-occluding state and,if the retention arrangement ceases to provide attachment to the body,the self-occlusion mechanism assumes a second state in which theself-occlusion mechanism occludes fluid flow through the cannula. Thecurrent invention occludes flow through the cannula by occluding thefluid flow passageway at any point along the flow passageway as will beevident in the following implementations.

Turning now to FIGS. 1-4, a first cam form of a constriction-basedimplementation of the present invention includes a cannula 3, aconstriction cam 4 for occluding fluid flow through the cannula 3, a camlever 5 for detecting proximity to the patient's body, a cam leverrecess 6, and a leaf-spring 7 for biasing the cam lever 5. Theconstriction cam 4 is rotatably mounted on the underside of the unit sothat it has the angular freedom of motion enabling it to rotate in afirst direction to the point in which the cam 4 constricts the cannula 3and to rotate in the opposite direction thereby moving the cam 4 awayfrom the cannula 3.

The cam lever 5 is connected on the constriction cam 4 so that thelever's substantially vertical motion in reference to the horizontalplane defined by the underside of the unit translates into angularmotion of the constriction can 4. The cam lever 5 is disposed on theconstriction can 4 so that when the lever 5 is seated in the cam leverrecess 6 the constriction cam 5 is disposed away from the cannula 3 andwhen the cam lever 5 is situated outside of the recess 6, theconstriction can is disposed to occlude the cannula 3. A leaf spring 7biases the cam lever 5 so that the default position of the cam lever 5is outside of the lever recess 6. An adhesive material is applied to thebottom surface 8 of the infusion unit to retain the infusion unit on thepatient's body. The constriction cam 4 is configurable to constrict thecannula 3 by rotating in a clockwise direction as shown if FIGS. 4A and4B or in a counter clockwise direction as shown in FIGS. 2 and 3. Theamount of torque needed to sufficiently constrict the cannula is afunction of the ease of wall deformation of the cannula 3.

Turning now to the operation of the device, in the default configurationthe cam lever 5 protrudes from the lever recess 6 and the constrictioncam 4 is disposed in its occluding position. Upon attachment the unitthe patient's body pushes the cam lever 5 into the cam lever recess 6and correspondingly rotates the constriction cam 4 away from the cannula3 enabling the uninhibited flow of medication. The cannula 3 is insertedinto the patient's body with an insertion needle as most clearly shownseen in FIG. 6 designation 11. When the unit detaches from the patient'sbody the constriction lever 5 is free to rotate into its biased positionthereby rotating the constriction cam 5 to the point at which it appliessufficient force to constrict the cannula 3. The resulting pressureincrease then trips the system's traditional pressure responsive alarm.

FIGS. 5-7 depict a second cam variant form of the constriction-basedembodiment including a pivotally mounted constriction lever 5 foroccluding the cannula 3, a compression spring 10 for biasing theconstriction lever 5 into a default occluding position.

The compression spring 10 is disposed at a near horizontal anglerelative to the horizontal plane defined by the base of the unit therebyvariably biasing the constriction element 5 so that it applies a minimumforce to the patient's body while attached and applies an increasingforce to the cannula 3 is it rotates so that the maximum constrictingforce is applied to the cannula 3 when the constriction lever hasachieved the maximum degree of rotation. This functionality is a resultof an increasing horizontal component of the force applied by the spring10 to the constriction element 5 as the angle between the constrictionelement 5 and the spring 10 increases. This feature ensures that theconstriction element 5 does not push the infusion set off the body whilestill developing sufficient torque to constrict the cannula 3. It shouldbe noted that the variable bias feature is preferably incorporated inall the embodiments employing a bias element to detect loss of contactwith the patient's body.

FIGS. 8-10 illustrate a slideable-block form of a constriction-basedembodiment include an infusion set housing 20, a slideable-blockstructure 21, a cannula 24, a lever 22 for detecting proximity to thepatient's body, a geared axle 26 connected to lever 22 for translatingsubstantially vertical motion of the lever 22 into lateral motion of theslideable-block structure 21, and a compression spring 23 forresiliently biasing the slideable block structure 23 into a defaultoccluding position. The slideable block structure 23 includes a toothedinterface 25 for the intermeshing of a geared axle 26, a spring guide27, a lip structure 28 for communicating with a corresponding lipstructure along the inner wall of the unit housing 20. The slideableblock structure 21 is disposed in the infusion set housing 20 so as toslide horizontally along the length of the unit. The horizontal mobilityis provided by the block structure lip 28 communicating with thecorresponding unit housing lip (not shown). The compression spring 23,disposed in the block structure 27, resiliently biases the blockstructure 21 into a default occluding position. The geared axle 26 withthe attached lever 22 is seated in the block-structure toothed interface25 so as to translate substantially vertical motion of the attachedlever 22 into lateral motion of the block structure 21 and vice versa.The lever 22 is disposed so that while the block structure 21 is in itsdefault occluding position the lever 22 correspondingly protrudes fromthe underside of the unit and as the lever 22 rotates into the undersideof the unit the block structure 21 moves laterally away from the cannula24 enabling the free flow of liquids. It should be noted that all of theslideable-block embodiments slide along a corresponding lipappropriately disposed along the inner wall of the unit housing.

As mentioned above the operation of the device is analogous in each ofthe embodiments and their variants.

FIG. 11 illustrates a second slideable-block variant form of aconstriction-based embodiment including a cannula 24, a foldable elementfor translating proximity to the patient's body to proximity of theslideable block-structure 21 to the cannula, a slideable block structure21 and a compression spring 23 for biasing the slideable block-structure21 into a default occluding position. The foldable element 29 includestwo sequentially and pivotally connected segments configured to assumeeither a partially folded or a fully extended configuration. Thefoldable element 29 is operative to assume a partially folded,protruding configuration when the slideable block structure is in itsdefault occluding position and to assume a fully extended,non-protruding configuration when the slideable block structure 21 hasassumed a non-occluding position.

FIGS. 12-14 illustrate a third slideable-block variant form of aconstriction-based embodiment employing a three-segment structureintegrally connected so as to form an effective hinge at each junction.This variant form includes a slideable constriction element 40 forconstricting the cannula 24, position transformation members 41 and 39for transforming a position of a proximity to the patient's body into acorresponding position of the sliding constriction element 40, acompression spring 23 for biasing the constriction element 40 into adefault occluding position. Prior to attachment to the patient's body,the compression spring 23 biases the constriction element 40 to slidealong a track disposed along the inner wall of the unit housing 20 so asto occlude the cannula 21 and furthermore to cause element 41 to pivotat integral joint 42 so as to be disposed at an angle causing proximityelement 39 to pivot at integral joint 43 away from the underside of theunit. This is the default occluding position the unit assumes whenunattached to the patient's body. Upon attachment to the patient's bodythe elements pivot in opposite directions thereby sliding theconstriction element 40 into its non-occluding position allowing theuninhibited flow of liquids through the infusion set.

FIGS. 15-17 illustrate a spring variant form of a constriction-basedembodiment employing a leaf spring 45 as the occluding element. The leafspring is configured so that when the infusion set in unattached to thepatient's body the leaf spring is resilient biased to press against thecannula 46 thereby occluding it and when the infusion set is attached tothe patient's body, the body pushes leaf spring away from the cannulathereby allowing the uninhibited flow of liquids

FIGS. 18-22 illustrate a first form of blockage-based embodimentemploying a sleeve diaphragm to block fluid flow through the infusionset. This embodiment includes a cannula 50, a constriction lever 51, acompression spring 56, a flow capillary 54, a sleeve shaped diaphragm53, a block structure 57 for anchoring the lower edge of the diaphragm53, a vertically displaceable collar 52 for adjusting the height of thediaphragm 53 and a diaphragm groove 55, The sleeve is disposedvertically around the block structure 57. The lower edge encircling theblock structure 57 is fastened to the block structure 57 and the upperedge is folded over so that it extends downward along the outer surfaceof the inner fold and fastened to the displaceable collar 52. Such aconfiguration provides a height adjustable diaphragm 53 being heightenedor being lowered as the displaceable collar 52 advances upwards ordownwards. A circular groove 55 is formed in the infusion set above theline of motion of the diaphragm. The diaphragm fold meshes with thisgroove when the diaphragm is disposed in its uppermost position.

A capillary bore through the body of the infusion set serves as a fluidpassageway 54. The bore is disposed to intersect the diaphragm groove 55so that the upper surface of the diaphragm fold serves as the bottomportion of the passageway wall while the diaphragm is disposed in itslowest position. When the diaphragm is disposed in its uppermostposition the diaphragm meshes with diaphragm groove 55 thereby blockingthe passage of liquids. The displaceable collar 52 is pivotallyconnected to the resiliently biased lever 51 so as to upwardly displacethe collar 52 upon detachment of the infusion set from the patient'sbody thereby occluding the flow passageway 54.

FIGS. 23-25 illustrate a second variant form of a blockage-basedembodiment employing a stopper. This variant form includes a cannula 60,a cannula inlet 64, a flow passage 61, a stopper 62 for plugging thecannula inlet 64, a displaceable stopper mount 63 providing vertical 62mobility. The stopper 62 is made of a sealant material and shaped toplug the cannula inlet thereby preventing the passage of liquids throughthe cannula. The stopper 62 is mounted on the stopper mount 63 thatextends vertically downwards so that when the bottom extremity rests onthe patient's body when the infusion set is attached to the body, themount supporting the stopper 63 maintains the stopper 62 above thecannula inlet 64 thereby enabling the uninhibited flow of liquidsthrough the cannula. As soon as the stopper mount 63 looses contact withthe body it moves vertically downwards consequently lowering theattached stopper onto the cannula inlet 64 thereby blockings thepassageway to fluid flow. The mount 63 is biased to move downwards via aspring (not shown) so that the default position will be the occludingposition.

FIGS. 26-27 illustrate a self-kinking embodiment employing aself-kinking cannula 70 in its operative non-occluded state and occludedstate respectively. The cannula 70 is inserted in its non-kinkedconfiguration and upon detachment from the patient's body assumes akinked configuration forming a substantially ninety-degree angle betweenthe two cannula portions connecting at the kink point sufficient toprevent the passage of liquids. This functionality is achieved byforming the cannula 70 from shape memory polymers so as to establishpermanent kinked occluding configuration and a temporary operativesubstantially straight configuration. After insertion in the patient'sbody, the natural body heat awakens the dormant kinked configuration andis restrained from assuming such a configuration by the patient's body.As soon as the cannula 70 is removed from the body it is free to assumeit's kinked, occluding configuration. Alternatively, this functionalitymay be achieved by forming the cannula 70 into a kinked configurationwith sufficient flexibility to be flexed into a straightened operativeconfiguration by an insertion needle.

A variant form of this kink embodiment employs a constriction mechanismin which the constriction occurs between a flat surface and a sharp edgeas most clearly seen in FIGS. 11A and 11B. Such constriction geometrycauses the cannula to bend acutely thereby occluding the passage ofliquids

FIG. 28 depicts the medicine delivery system in which the currentinvention operates. As illustrated, the system includes a medicine pump75 connected to an attachable infusion set 76 attached to the patient'sbody via an adhesive patch 77. Pull-tabs 78 are provided to facilitateremoval.

It will be appreciated that the above descriptions are intended only toserve as examples, and that many other possible embodiments are withinthe scope of the present invention as defined in the appended claims.

What is claimed is:
 1. A device for supporting a cannula duringadministering of a fluid through the skin, the device comprising: (a) abase comprising a holder for retaining a cannula in a cannula positionsuitable for administering a fluid through the skin, said base having askin contact surface for adhesive attachment to the skin; (b) amechanical sensing element retained in a first position relative to saidbase by contact with the skin while said skin contact surface isattached to the skin, said mechanical sensing element being displaceableto a second position when said skin contact surface is detached from theskin; and (c) an occluding element mechanically biased to move relativeto said base from a non-occluding position to an occluding position,said occluding position being such that, when a cannula is retained insaid cannula position, said occluding element acts on the cannula to atleast partially occlude flow through the cannula, said occluding elementbeing mechanically linked to said mechanical sensing element so as to beselectively retained in said non-occluding position while saidmechanical sensing element is in said first position.
 2. The device ofclaim 1, wherein said mechanical sensing element is pivotally linked tosaid base.
 3. The device of claim 1, wherein said occluding element isslidingly engaged with said base so as to slide from said non-occludingposition to said occluding position.
 4. The device of claim 3, furthercomprising a compression spring deployed to bias said occluding elementto slide from said non-occluding position to said occluding position. 5.The device of claim 3, wherein a direction of said sliding engagement issubstantially parallel to said skin contact surface.
 6. The device ofclaim 1, wherein said mechanical sensing element extends on two opposingsides of said cannula position.
 7. The device of claim 1, furthercomprising adhesive deployed on at least said skin contact surface.
 8. Adevice for supporting a cannula during administering of a fluid throughthe skin, the device comprising: (a) a base comprising a holder forretaining the cannula in a cannula position suitable for administering afluid through the skin, said base having a skin contact surface providedwith a layer of adhesive for attachment to the skin; (b) a mechanicalsensing element pivotally mounted to said base and retained in a firstposition relative to said base by contact with the skin while said skincontact surface is attached to the skin, said mechanical sensing elementbeing pivotally displaceable to a second position when said skin contactsurface is detached from the skin; and (c) an occluding elementslidingly engaged with said base and mechanically biased to slide from anon-occluding position to an occluding position, said occluding positionbeing such that, when a cannula is retained in said cannula position,said occluding element acts on the cannula retained in said cannulaposition to at least partially occlude flow through the cannula, saidoccluding element being mechanically linked to said mechanical sensingelement so as to be selectively retained in said non-occluding positionwhile said mechanical sensing element is in said first position.
 9. Thedevice of claim 8, further comprising a compression spring deployed tobias said occluding element to slide from said non-occluding position tosaid occluding position.
 10. The device of claim 9, wherein a directionof said sliding engagement is substantially parallel to said skincontact surface.
 11. The device of claim 8, wherein said mechanicalsensing element extends on two opposing sides of said cannula position.